In vitro sealing of iatrogenic fetal membrane defects by a collagen plug imbued with fibrinogen and plasma

A collagen plug with shape memory to seal iatrogenic fetal membrane defects after fetoscopic surgery

Iatrogenic preterm premature rupture of fetal membranes (iPPROM) after fetal surgery remains a strong trigger for premature birth. As fetal membrane defects do not heal spontaneously and amniotic fluid leakage and chorioamniotic membrane separation may occur, we developed a biocompatible, fetoscopically-applicable collagen plug with shape memory to prevent leakage. This plug expands directly upon employment and seals fetal membranes, hence preventing amniotic fluid leakage and potentially iPPROM.

Lyophilized type I collagen plugs were given shape memory and crimped to fit through a fetoscopic cannula (Ø 3 mm). Expansion of the plug was examined in phosphate buffered saline (PBS). Its sealing capacity was studied ex vivo using human fetal membranes, and in situ in a porcine bladder model.

The crimped plug with shape memory expanded and tripled in diameter within 1 min when placed into PBS, whereas a crimped plug without shape memory did not. In both human fetal membranes and porcine bladder, the plug expanded in the defect, secured itself and sealed the defect without membrane rupture.

In conclusion, collagen plugs with shape memory are promising as medical device for rapid sealing of fetoscopic defects in fetal membranes at the endoscopic entry point.

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Shape memory can be given to collagen plugs to rapidly expand in aqueous fluids.

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Within 1 min in aqueous fluid, collagen plugs with shape memory triple in diameter.

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Collagen plugs with shape memory show potency to seal fetal membrane defects.

Application of Tissue Engineering and Regenerative Medicine in Prelabor Rupture of Membranes: a Review of the Current Evidence

Preterm prelabor rupture of membranes (PPROM) is the main cause of preterm delivery, resulting in increased perinatal morbidity and mortality. Several techniques have been studied for the healing of ruptured membranes, with some success. Before new techniques using tissue/organ engineering are applied in clinical practice, these techniques must be validated in clinical trials. To address this issue, the objective of this study was to summarize the current literature on interventions to seal or heal the amniotic membranes after PPROM. An electronic search was conducted using the keywords "fetal membranes," "premature rupture," "amnion," "tissue engineering," "fibrin tissue adhesive," "regenerative medicine," "tissue adhesive," "wound healing," and "fetoscopy" through the MEDLINE, Embase, and Cochrane CENTRAL databases, with the limitation of English-language studies. Through a review of the identified studies, it was found that spontaneous healing of the fetal membrane has not been successful. Several efforts have been made to seal membranes before or after rupture using different methods, including amniopatches, collagen, tissue patches, fibrin sealant, mussel-mimetic sealant, engineered cell matrix, and immunological supplements. However, most studies have been conducted in ex vivo or in vivo settings, so the safety and applicability of these techniques to spontaneous rupture of membranes in clinical settings have not been sufficiently tested. Overall, the current evidence is limited regarding the safety and effectiveness of interventions against PPROM.

Tissuepatch is biocompatible and seals iatrogenic membrane defects in a rabbit model

OBJECTIVE

To evaluate novel sealing techniques for their biocompatibility and sealing capacity of iatrogenic fetal membrane defects in a pregnant rabbit model.

METHOD

At day 23 of gestation (term = d31), a standardized fetoscopy was performed through a 14G cannula. The resulting fetal membrane defect was closed with condensed collagen, collagen with fibrinogen, Tissuepatch, Duraseal, or a conventional collagen plug (Lyostypt) as reference. At d30, the fetuses were harvested and full thickness fetal membrane samples were analyzed. The study consisted of 2 consecutive parts: (1) biocompatibility testing by fetal survival, apoptosis, and infiltration of polymorphonuclear cells in the membranes and (2) the efficacy to seal fetal membrane defects.

RESULTS

Three sealants (collagen with fibrinogen, Duraseal, or Lyostypt) were associated with a higher fetal mortality compared to control unmanipulated littermates and hence were excluded from further analysis. Tissuepatch was biocompatible, and amniotic fluid levels were comparable to those of control untouched littermates. Compared to the condensed collagen, Tissuepatch was also easier in surgical handling and induced limited cell proliferation.

CONCLUSION

Tissuepatch had the best biocompatibility and efficacy in sealing an iatrogenic fetal membrane defect in the pregnant rabbit compared to other readily available sealants.

Thrombin Generation by Fetoscopic Trauma to the Fetal Membranes: An in vivo and in vitro Study

OBJECTIVE

We first aimed to investigate in vivo thrombin generation induced by fetoscopy, and second we used term membrane explants for measurement of thrombin generation, thrombin receptor location and induction of selected matrix metalloproteinases (MMPs) in tissue culture.

MATERIALS AND METHODS

In vivo study (37 cases): samples of amniotic fluid were taken at the beginning and end of fetoscopy (mean gestational age 26.7 weeks) and analyzed by ELISA for thrombin-antithrombin complexes. In vitro study: fetal membranes were put in culture and punctured for measurement of thrombin generation by calibrated automated thrombography and ELISA. Induction of MMP-9 and MMP-2 was analyzed by zymography. PAR-1 was localized by immunohistochemistry.

RESULTS

No significant increase in thrombin-antithrombin was measured in amniotic fluid obtained during fetoscopy. In vitro, thrombin generation induced by needle trauma of membrane cultures is correlated to the amount of plasma. Activity of MMP-9 but not MMP-2 was elevated in cultured membranes but could not be inhibited by a thrombin inhibitor. On histology, the thrombin receptor PAR-1 was located in the chorion and decidua, but not in the amnion.

DISCUSSION

Despite the influence of thrombin on punctured fetal membranes in vitro, the role of thrombin in iatrogenic preterm premature rupture of membranes is questionable.

Collagen plug sealing of iatrogenic fetal membrane defects after fetoscopic surgery for congenital diaphragmatic hernia

OBJECTIVES

To investigate the efficacy of collagen plugs at reducing the risk of preterm premature rupture of membranes (PPROM) after fetoscopic surgery for congenital diaphragmatic hernia (CDH).

METHODS

This was a single-center cohort study on all consecutive cases undergoing fetoscopic endoluminal tracheal occlusion (FETO) for severe or moderate CDH, between April 2002 and May 2011 (n = 141). Cases either received a collagen plug for sealing the fetal membrane defect after FETO or did not, depending on the operating surgeon. The principal outcome measure was the time from fetal surgery to PPROM, further referred to as 'latency'. A multivariable Cox regression model was used to investigate the association between collagen plug and latency while adjusting for risk factors for PPROM.

RESULTS

Of the 141 cases, 54 (38%) received a collagen plug and 87 (62%) did not. Sixty cases experienced PPROM, 26 among cases with and 34 among cases without a plug (48 vs 39%). The hazard ratio of plug use was 1.29 (95% CI, 0.76-2.19), which does not exclude a potentially increased risk for PPROM when a collagen plug is used. For cases with a plug, 24% had PPROM before balloon removal and 24% had PPROM after elective balloon removal. For cases without a plug, these rates were 30 and 9%, respectively. Perinatal outcomes were similar in both groups.

CONCLUSIONS

No evidence was found that collagen plugs reduce the risk of PPROM after FETO for CDH.